我国人口地理界线[ ]
A.以黑龙江省的黑河市与云南省的腾冲县的连线为界
B.以秦岭——淮河一线为界
C.以长江为界
D.以黑龙江省的漠河至海南的海口一线为界
答案:A
The fans were well behaved and the game was played without _____.[ ]
A. action
B. accident
C. event
D. matter
当主动件等速连续转动,需要从动件做单向间歇转动,可采用()机构。
A.连杆机构
B.凸轮
C.不完全齿轮